Thread: 3 Way Valet Switch Diagram - Transister Needed?

you could get away with a pair of diodes there, to prevent your domelight from backfeeding into your ignition or vice versa. but your 07 civic should have switched ground not switched 12v at the domelight. if you add a relay on that switched ground you can switch the polarity and it sounds like you would be in buisiness

Thanks I didn't know that it was the negative that was switched.

So I think I understand the use of the relay (after three edits lol)



Would it make a difference if I were to use a coil or photo isolated based relay?

Thanks

i would use a standard spdt bosch style automotive relay and the funky little black boxes are diodes. sorry i dont have photoshop so this is a mockup from paint

no problem as long as it gets the point across ^_^

Thanks a lot!

no prob

Heres an updated version thats a little clearer for anyone thats interested.



So regarding the -12VDC... where is that coming from exactly if the "switched ground from dome light" would be the negative on the light.

Thanks

it would be the same as the 12v constant wired at the switch

gotcha, thanks!

once again no prob